Even a faux rapper nickname couldn't save Tim Pawlenty's short-lived presidential candidacy, which came to an end after the former Minnesota governor's disappointing finish in the Ames Straw Poll.

As the New York Times' Matt Bai writes, what ultimately sank the Pawlenty campaign was the absence of a clear reason why Republican voters should have backed Pawlenty over any of the other candidates. Though Pawlenty skewered Democrats and offered a number of straightforward policy proposals, he failed to explain why he was the party's best bet for taking on Obama in 2012.

"But the more salient lesson here, it seems to me, has little to do with Mr. Pawlenty’s resume or his strategy," Bai writes. "If you want to run for president, especially as a little-known establishment candidate, it usually helps if you have something to say."

Romney, on the other hand, has made strides recently to "articulate a simple and elegant" rationale for why he's the best option in the Republican field, arguing that he, unlike Obama, knows how to boost the economy and create jobs.

Pawlenty's problem wasn't unique to his campaign. Bai notes that Jon Huntsman has also, at least so far, failed to offer a "core argument" for his candidacy. And even Rick Perry, for all the fanfare around his entrance into the race, still has a way to go to define himself as well. If he fails to do that, Bai warns that if he fails to do so Perry may wind up as just another speaker -- and not the nominee -- at the GOP convention next year.